In this article, we will list the 5 Best Renewable Energy Penny Stocks to Buy. Please visit 11 Best Renewable Energy Penny Stocks to Buy if you’d like to see an extended list and how we came up with the list of best renewable energy penny stocks.

5. Tigo Energy, Inc. (NASDAQ:TYGO)

Number of Hedge Fund Holders: 12

Tigo Energy, Inc. (NASDAQ:TYGO) is one of the best renewable energy penny stocks to buy.

On March 9, 2026, Tigo Energy said it entered a strategic partnership with CELTEC, a regional distributor of renewable energy products, to expand distribution of Tigo Rapid Shutdown solutions, optimizers, and other products across Central America and the Caribbean. The company said the deal is aimed at improving safety and regulatory compliance as solar adoption grows across those markets.

Tigo said the partnership will help broaden access to technologies aligned with NEC 2017 and NEC 2020 requirements, which are already mandatory in Panama and are being adopted more widely across Central American and Caribbean markets. CELTEC CEO Darío Torres said the implementation of NEC 2020 changes how solar projects are designed, especially regarding first-responder safety.

A key product of the collaboration is Tigo’s TS4-A-2F rapid shutdown solution. The company said the product complies with module-level shutdown requirements under NEC 2017/2020 and carries IEC, UL, and UL PVRSS certifications. Tigo also said the TS4-A-2F connects to two modules and can reduce installation time while enabling up to 16% fewer connections in a 14-panel string versus single-channel MLPE systems.

Founded in 2007, Tigo Energy, Inc. (NASDAQ:TYGO) develops smart hardware and software for solar systems, including module-level power electronics, monitoring platforms, inverters, and battery storage products for residential, commercial, and utility-scale applications.

4. Clean Energy Fuels Corp. (NASDAQ:CLNE)

Number of Hedge Fund Holders: 21

Clean Energy Fuels Corp. (NASDAQ:CLNE) is one of the best renewable energy penny stocks to buy.

On March 4, 2026, Clean Energy Fuels Corp. said it signed and extended a series of renewable natural gas-related agreements across trucking, refuse, transit, municipal, and airport fleets in the U.S. The company said the deals cover both RNG supply and fueling infrastructure services, reflecting continued adoption of the fuel across multiple end markets.

Among the announced agreements, Ecology Transportation Services will fuel its 150-vehicle RNG trucking fleet through Clean Energy under a deal expected to cover about 2.1 million gallons annually across California, Arizona, and Nevada. WMATA also extended its relationship with the company under a new operations and maintenance contract tied to five million gallons of fuel for more than 400 buses.

The release also said Clean Energy will provide RNG to 78 Arlington Transit buses, totaling roughly 750,000 gallons annually, while Phoenix-area transit infrastructure maintained by the company supports 335 natural gas buses and dispenses about 4.7 million gallons per year. Other agreements mentioned Recology, Scottsdale, Nashville International Airport, and Fort Smith. Senior Vice President Chad Lindholm said fleets are choosing RNG because it is clean, affordable, domestically produced, and supported by an established fueling network.

Clean Energy Fuels Corp. (NASDAQ:CLNE) is a U.S. provider of renewable natural gas and fueling solutions for transportation fleets. The company operates fueling stations across the U.S. and Canada and also develops RNG production facilities at dairy farms.

3. SunPower Inc. (NASDAQ:SPWR)

Number of Hedge Fund Holders: 22

SunPower Inc. (NASDAQ:SPWR) is one of the best renewable energy penny stocks to buy.

On March 11, 2026, SunPower disclosed in an SEC filing that it had entered into a purchase agreement with YA II PN, Ltd., dated March 6, 2026, under which the investor agreed to buy a convertible debenture with a principal amount of $10 million. The purchase price was set at 90% of that amount, meaning SunPower is raising less cash than the debenture’s face value.

The debenture carries a 0% annual interest rate unless an event of default occurs, in which case the rate rises to 18%. It matures on March 6, 2027, unless extended at the holder’s option. The repayment schedule attached to the debenture shows five monthly principal installments of $2 million, due from May 5, 2026, through September 5, 2026, with a 3% payment premium on those installments, for total scheduled payments of $10.3 million.

SunPower also signed a registration rights agreement tied to the deal. Under that agreement, the company is required to file the initial resale registration statement by April 30, 2026. The filing also noted that the transaction is subject to an exchange cap of 22,381,878 shares, unless stockholders approve issuance above that limit under Nasdaq rules.

SunPower Inc. (NASDAQ:SPWR) is a U.S.-based solar company focused on residential solar, battery storage, and related energy solutions.

2. Energy Vault Holdings, Inc. (NYSE:NRGV)

Number of Hedge Fund Holders: 24

Energy Vault Holdings, Inc. (NYSE:NRGV) is one of the best renewable energy penny stocks to buy.

On March 3, 2026, Energy Vault said it closed an upsized $150 million financing in convertible senior notes, above the $125 million size it had initially announced. The company said the deal was aimed at strengthening its balance sheet and supporting execution of its own-and-operate strategy.

Energy Vault also said it used part of the proceeds to repay existing higher-cost debt. Specifically, on February 19, 2026, the company redeemed about $45 million in aggregate principal amount of senior unsecured convertible debentures previously issued to YA II PN, Ltd., an affiliate of Yorkville Advisors. According to the release, it removed the principal from Energy Vault’s balance sheet and improved future financial flexibility.

The company added that it entered into a capped call derivative transaction at a 100% premium to the pre-announcement closing price of $4.06, resulting in an effective future conversion price of $8.12 per share. Energy Vault said the structure was designed to reduce potential dilution.

Management linked the financing to what it described as strong preliminary 2025 results, including above-consensus revenue, gross margin, and total cash, as well as progress toward profitability. Chairman and CEO Robert Piconi said the company achieved positive adjusted EBITDA in the fourth quarter and increased cash and liquidity sequentially through the year. Energy Vault said it would provide full fourth-quarter and full-year 2025 results, along with its 2026 outlook, on March 17, 2026.

Energy Vault Holdings, Inc. (NYSE:NRGV) develops, deploys, and operates utility-scale energy storage systems. Its offerings include battery, gravity, and green hydrogen storage technologies, supported by an energy management software and integration platform for utilities, independent power producers, and large industrial users.

1. Plug Power Inc. (NASDAQ:PLUG)

Number of Hedge Funds: 29

Plug Power Inc. (NASDAQ:PLUG) is one of the best renewable energy penny stocks to buy.

On March 9, 2026, Jefferies cut its price target on Plug Power Inc. (NASDAQ:PLUG) to $1.80 from $2.00 while maintaining a Hold rating, pointing to concerns about whether the company’s improving margin profile can be sustained. The note said Plug reiterated its expectation for positive EBITDA in 2026, but Jefferies still views that outlook as a “show me” story. The firm also said Plug’s fourth-quarter gross margin benefited partly from one-off items, even as it acknowledged better liquidity and expected performance support from material handling and electrolyzers in 2026.

For context, Plug reported fourth-quarter 2025 revenue of $225.2 million, up 17.6% from the prior-year quarter, while full-year 2025 revenue rose 12.9% to about $710 million. The company posted a positive fourth-quarter gross profit of $5.5 million, or 2.4% of sales, versus a gross margin loss of negative 122.5% a year earlier. Management said the improvement was driven by higher sales volume, a better mix, price increases on some offerings, fuel network enhancements, lower service cost per unit, and manufacturing efficiency gains tied to Project Quantum Leap.

Plug also ended 2025 with $368.5 million in unrestricted cash, said an asset monetization agreement is expected to generate more than $275 million, and reported that net cash used in operations fell 26.5% year over year to $535.8 million.

Plug Power Inc. (NASDAQ:PLUG) develops hydrogen fuel cell systems, electrolyzers, hydrogen production infrastructure, and related solutions for material handling, industrial, and energy markets.

While we acknowledge the potential of PLUG to grow, our conviction lies in the belief that some AI stocks hold greater promise for delivering higher returns and have limited downside risk. If you are looking for an AI stock that is more promising than PLUG and that has 100x upside potential, check out our report about this cheapest AI stock.

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